1. Field of the Invention
The present invention relates generally to polymer gums and methods for modifying such gums by direct fluorination with fluorine. More particularly, the present invention relates to the fluorination of uncross-linked gums to provide novel fluorinated gums which may be used in the fabrication of a wide variety of polymeric compounds and materials.
2. Description of Related Art
Elastomers are typically polymeric materials possessing an inherent property known as elasticity which allows them to return to their original form when released from a deforming load and which are capable of a substantial degree of stretching under tension before breaking. Elastomers are used in a wide range of applications which include (but are not limited to): Static and dynamic seals, couplings, rollers, bearings, bushings, diaphragms, gears and shock absorbers. In these and other applications, the elastomer is frequently subjected to a variety of hostile conditions and environments which often compromise its performance. For example, the elastomer may be exposed to high temperatures, high pressures, corrosive fluids, and abrasive media, all of which can limit the usefulness of an elastomer in such an environment. In addition, elastomers tend to exhibit high inherent friction and poor wear characteristics which can result in uneven performance and again limit their usefulness in certain applications.
Several methods of improving some of these undesirable properties are currently used in industry. For example, to counter the poor abrasion resistance of certain elastomers it is common to add to the elastomer formulation what is referred to as a "process aid" or "internal lubricant". During operation, a lubricative layer is formed between the elastomer and mating surface, which lowers friction and , to some extent, increases wear life. Another common technique is to coat the finished elastomeric articles with a thin layer of polytetrafluoroethylene (PTFE) which can improve the friction characteristics of the article and if it does not wear away, can offer some improvement in chemical resistance by acting as a barrier.
However, the benefits which arise from these and other techniques are generally only short term in that the root of the problem 13 i.e. the structure of the elastomeric polymer--is not addressed. As soon as the coating or additive wears away or leaches out of the article, the problem returns.
It would be highly desirable, therefore, to provide polymer compositions that can be used to make elastomeric articles which can withstand aggressive environments for extended periods of time. The polymer compositions should be amenable to use alone or in combination with other polymers to provide a wide variety of polymeric materials. Further, the polymer compositions should be compatible with conventional fillers, plasticizers and other additives so that the various physical characteristics of the final elastomeric article can be tailored to meet specific operational requirements within the aggressive environment.